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Slip Sliding Away: Load-Dependence Of Velocity Generated By Skeletal Muscle Myosin Molecules In The Laser Trap, Edward P. Debold, Joseph B. Patlak, David M. Warshaw
Slip Sliding Away: Load-Dependence Of Velocity Generated By Skeletal Muscle Myosin Molecules In The Laser Trap, Edward P. Debold, Joseph B. Patlak, David M. Warshaw
Edward P. Debold
Skeletal muscle's ability to shorten and lengthen against a load is a fundamental property, presumably reflecting the inherent load-dependence of the myosin molecular motor. Here we report the velocity of a single actin filament translocated by a mini-ensemble of skeletal myosin ∼8 heads under constant loads up to 15 pN in a laser trap assay. Actin filament velocity decreased with increasing load hyberbolically, with unloaded velocity and stall force differing by a factor of 2 with [ATP] (30 vs. 100 μM). Analysis of actin filament movement revealed that forward motion was punctuated with rapid backward 60-nm slips, with the slip …